Thermally annealed wafer-scale h-BN films grown on sapphire substrate by molecular beam epitaxy
Fang Liu, Xin Rong, Ye Yu, Tao Wang, Bowen Sheng, Jiaqi Wei, Sida Liu, J. J. Yang, F. Bertram, Fujun Xu, Xuelin Yang, Zhenhua Zhang, Z. X. Qin, Y. T. Zhang, Bo Shen, Xinqiang Wang
Abstract
The effect of high temperature annealing (HTA) on crystalline quality improvement of h-BN films grown on sapphire substrates has been investigated. It is found that BN grown using conventional molecular beam epitaxy is disordered due to the growth temperature below 1000 °C. By annealing at a temperature of 1700 °C, thermodynamically stable crystalline h-BN could be obtained at wafer scale, where diffusion of atoms in the as-grown BN film is enhanced and the structural defect density decreases. The crystalline h-BN has been confirmed by x-ray diffraction, Raman scattering, and atomic force microscopy measurements. This work demonstrates that HTA is a simple and effective way to achieve wafer-scale crystalline h-BN films, which have numerous potential applications in next-generation two-dimensional devices and flexible III-nitride optoelectronic devices.